(i) Field of the Invention:
This invention relates to stable external medicinal preparations useful for the healing of damaged skin (hereinafter abbreviated as "wounds" for the sake of brevity) such as burns, decubitus and open wounds. More specifically, it is concerned with wound-healing preparations which contain a sugar and povidone-iodine (polyvinylpyrrolidone-iodine complex) as effective ingredients.
(ii) Description of the Prior Art:
Sugars such as honey and molasses have conventionally been used, as folk therapy, for the treatment of burns and open wounds. These sugars have also been known to have bacteriostatic action and granulation tissue growth-promoting effects. Povidone-iodine is a drug employed extremely widely as an antiseptic throughout the world.
It has recently been reported that excellent wound-healing effects were achieved when granulated sugar was mixed with povidone-iodine preparations such as "Betadine" (trade mark of The Purdue Frederick Co., Norwalk, Connecticut, U.S.A.) ointment, "Betadine" solution and "Isodine Gel" (trade mark; product of Meiji Seika Kaisha, Ltd., Tokyo, Japan) and the resultant mixtures were applied to various wounds [R.A. Knutson et al., "Southern Medical Journal", 74(11), 1329-1335 (1981); and Kiyokazu Sone et al., "Byoin Yakugaku (Hospital Pharmacology)", 10(5), 315-322 (1984)].
Further, Japanese Patent Application Laid-Open No. 141409/1980 of Nov. 5, 1980, which corresponds in part to U.S. Pat. No. 4,401,651 issued on Aug. 30, 1983, discloses a composition composed of 20 parts by weight of granulated sugar, 5 parts by weight of "Betadine" ointment and 2 parts by weight of "Betadine" solution. Although "Betadine" ointment and solution are povidone-iodine preparations produced and marketed in U.S.A. by The Purdue Frederick Co., they are not commercially available in Japan. Details of their ingredients are hence unknown to the present inventors.
The following problems were however found on compositions, which had been prepared respectively by mixing commercial povidone-iodine preparations available to the present inventors with a sugar in accordance with the formulation described in Japanese Patent Application Laid-Open No. 141409/1980 referred to above.
(1) The content of povidone-iodine in each of the commercial povidone-iodine preparations was not constant. The ratio of the sugar to povidone-iodine in the resulting composition hence varied from one production lot to another, whereby it was difficult to obtain compositions of uniform quality.
(2) The mixture of each of the commercial povidone-iodine preparation and the sugar has an extremely high viscosity. A special apparatus was therefore needed to perform uniform kneading. Furthermore, it was difficult to produce the composition in a large volume by a single mixing operation.
(3) When stored at room temperature, each of the compositions separated into two layers or was rendered like starch syrup and moreover, its effective ingredient underwent decomposition to reduce the drug efficacy. It was thus necessary to store the compositions in a cool and dark place. The effective ingredient was however decomposed in several months even when stored in the above manner. It was hence essential to prepare the compositions before use.
Among these problems, the problem (3) which requires the preparation of a composition before use is an extremely serious problem. The problem (3) has therefore led to such inevitable drawbacks that the composition cannot be prepared except for large hospitals equipped, for example, with the above-mentioned kneader, aseptic manipulation facilities, sterilization equipment and the like and patients must attend hospitals whenever administration is required.